This invention relates to a vacuum unit for producing a stroke movement by means of an applied vacuum.
German Patent Application DE 196 23 961 A1 discloses a vacuum unit in the form of a pneumatic switching element, which is connected to a vacuum source and has a pressure space in which is situated a control member that is displaceable by a vacuum against the force of a spring element. This control member is connected to an actuating device which extends out of the pressure space. The spring element is arranged outside of the pressure space and acts on the actuating device or may be mounted on an articulated joint situated outside of the pressure space. With this design, it is impossible to implement a guidance of the drive rod via the spring. In addition, there is the risk of the drive rod becoming skewed, so that the diaphragm of the vacuum unit rubs against the housing or comes to rest on it, which can damage the diaphragm. The diaphragm may also become frayed, which can result in failure of the vacuum unit. This results in inaccuracies in transmission of the vacuum to an element to be actuated.